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SYCQ: Symposium Correlated Quantum Matter – From Cold Atoms to the Solid State
SYCQ 1: Correlated Quantum Matter – From Cold Atoms to the Solid State
SYCQ 1.3: Invited Talk
Tuesday, September 9, 2025, 11:45–12:15, ZHG008
Giant transverse magnetic fluctuations at high fields in UTe2 — •Kimberly Modic1, Valeska Zambra1, Amit Nathwani1, and Brad Ramshaw2 — 1Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria — 2Cornell University, Ithaca, NY USA
Superconductors offer a rare glimpse into quantum mechanics at a macroscopic scale, making them powerful candidates for next-generation quantum technologies. While most superconducting qubits still rely on conventional materials like aluminum, a new class of unconventional superconductors-featuring exotic properties such as time-reversal symmetry breaking and nodal gaps-could enable new functionalities in quantum devices. Among these, UTe2 stands out for its extraordinary behavior: it regains its superconducting state at ultra-high magnetic fields above 40 tesla, after initially being suppressed around 10 tesla–a phenomenon known as re-entrant superconductivity. One proposed explanation involves transverse fluctuations of a ferromagnetic order parameter. Yet, UTe2 shows no clear signs of ferromagnetic order or strong fluctuations in standard magnetization measurements. To probe deeper, we developed a new technique to measure the transverse magnetic susceptibility in pulsed magnetic fields up to 60 tesla. In a manner reminiscent of the transverse field Ising model, large external magnetic fields applied along the b-axis lead to a huge increase in the transverse susceptibility–over 30 times greater than the longitudinal response. These findings suggest that the highly-unusual, magnetic field-enhanced superconductivity of UTe2 is closely linked to this anisotropic magnetic response.
Keywords: superconductivity; quantum criticality; transverse magnetic fluctuations; magnetotropic susceptibility; high magnetic fields